Froth flotation process for oxide ores



Patented May 7, 1935 UNITED STATES PATENT OFFICE John Mark Patek,Milwaukee, Wis.

No Drawing. Application July 16, 1934,

Serial No. 735,424

6 Claims.

This invention relates to an improvement in the process of concentrationby'fiotation of heavy mineral metal oxides and it consists in thetreating of such ores while in the state of a pulp with sufiicientactive acid, together with a saponiflable substance and awater-insoluble liquid ketone.

The heavy mineral metal oxides, among which may be named magnetite,corundum, ilmenite, rutile, chromite, cuprite, zincite, franklinite, andpyrolusite, or some of them, have been treated by flotation heretoforefor the purpose of concentrating the ores thereof. In such cases theratio of concentration has been low and unless the ore was initiallysufiiciently high grade the concentrate has not been of commercialvalue, that is, sufficiently free of gangue substances as to permiteconomical smelting operations. In the case of cassiterite there is norecord of a commercial concentrate having been produced by flotationdirectly from any natural ore. Generally speaking, therefore,concentration of oxide ores by flotation has heretofore been of verylittle commercial moment because of the low ratio of concentrationobtainable thereby.

Heretofore the flotation of heavy mineral oxide ores has been attemptedby employing silicates for depressing the gangue materials and frothingand collecting agents for recovering the ore. In

' this method an extremely critical balance between frothing,collecting, and depressing reagents needed to be maintained if resultsof any advantage were to be obtained. Even when performing under optimumconditions, such methods have been relatively ineffectual, producinga'low ratio of concentration.

The process of this invention, however, is positive in its action. Inthe case of certain ores the grade of concentrate is roughly independentof the percentage of the ore mineral in the pulp being treated. Forexample, a grade of concentrate of approximately sixty per cent tin canbe obtained effectually from cassiterite pulps containing all the wayfrom two to thirty percent of tin. In the process of this invention thereagents employed are effective over a substantial range ofconcentration and there are no critical balances which must bemaintained in order to obtain the results desired. The effects of thereagents are striking and easily recognizable and therefore the controlof the. operation is simplifled, due to the fact that visual and othersimple observations are all that is necessary in order to keep theprocess under control.

In this invention neither the amount of saponifiable substance norketone need be controlled so long as a suificient amount of each beusedand their action is not based upon the use of starvation amountsthereof. The acid employed is an active acid and its presence insufllcient quantities is very easily determined.

The process of this invention is carried on by reducing the ore to betreated to a proper pulp. This is done by grinding in any usual manner,or in case the particular material is in the form of 1 a slime or othervery finely divided state it may i be possible to treat the samedirectly. The pulp is fed into any one of the usual froth flotationmachines in which the proper agitation and aeration are provided. Thereis added to the feed of pulp, or in any other manner desired, a smallamount of a saponiflable substance. This substance may be any one of anumber of natural fatty acids, from fish, linseed, palm, cocoanut, tung,or red oil, or any high molecular weight, aliphatic or cyclic carboxylicacid, such as oleic acid, or oxidation products of normal or naphthenicpetroleum, or naphthenic acids derived from any other source. There isalso added a 3 frother consisting of insoluble liquid ketone. For thispurpose it has been found that the following will serve the purpose:

Iso-amyl phenyl ketone Iso-butyl phenyl ketone Di-iso-amyl ketoneDi-propyl ketone Di-iso-propyl ketone Ethyl benzyl ketone Ethyl butylketone Ethyl-iso-butyl ketone Ethyl octyl ketone Ethyl phenyl ketoneIso-butyl ketone Hexyl ketone Nonyl ketone Octyl ketone V n-propyliso-butyl ketone n-propyl phenyl ketone Iso-propyl phenyl ketonecentrated) acetic, or tartaric are suitable. At any rate, I havediscovered that certain ores combine with substantial amounts of acidand that a slight .excess thereover is necessary to obtain the suc.-cessful results of the process of this invention, the quantity not beingparticularly important so long as an excess is present and the apparatusin which the process is being carried on is reasonably free from attackby the acid.

The process as outlined above is carried on in. highly acid condition ascompared with flotation heretofore practiced. Under these conditionssaponifiable substances, such as described above, are without frothingpower and merely produce oiling, and are incapable of supporting anypulp. The discovery of this invention, however, depends to a certainextent upon the important fact that the sparingly soluble liquid ketoneproduces, with the saponiflable substance, 2. very strong frothregardless of the acidity of the pulp. Such frothers as have beencommonly employed, as pine oil, or cresol, if employed in an acid pulpsufliciently acid to effect gangue mineral to the extent necessary, whenused in combination with a fatty acid form drops in the flotation pulpand spread only with long and violent agitation of the pulp. The resultis generally over oiling, with no froth, or a poor, small bubble, orbrittle froth that fails to produce a concentrate. The sparingly solubleketones, however, not only produce a good froth when in combination withthe fatty acid, but the ketone also serves to spread the fatty acid. Itis advantageous at times, therefore, to dissolve a fatty acid in theketone and to add the combination to the flotation cell. Although theketone alone will produce a froth, such froth is brittle andineffective, while the addition of the fatty acid brings about a strongand effective froth.

At times the process of this invention may be practiced as follows: 1000grams of a cassiterite ore which has been ground in a ball mill areagitated and aerated in a flotation machine together with three grams ofhydrochloric acid (concentrated) and one pound of sulfuric acid (con- Tothis 0.87 of a gram of oleic acid and 0.15 gram of Barrett oil No. 635,which is a fluid coal tar or tarry oil, and 0.20 of a gram of dipropylketone. A froth will be formed which will contain probably in excess offifty per cent of tin, and in one specific case contained fifty-four percent of tin. In this case the pulp undergoing treatment contained thirtyper cent of tin.

The process of this invention at times may also be practiced as follows:The pulp of cassiterite ore is prepared as described above, to whichthere is added approximately three pounds of concentrated sulfuric acidper ton of dry ore and ten pounds of sodium fluoride per ton of dry ore,which in the presence of sulfuric acid forms hydrofluoric acid. There isalso added one-half pound of dipropyl ketone per ton of dry ore and 1.6pounds of oleic acid per ton of dry i re. The usual aeration andagitation treatment is carried on, producing a froth which may containapproximately sixty per cent of tin, for example, constituting as muchas ninety-six per cent of the tin in the ore being treated.

The process may also at times be carried on by treating an orecontaining, for example, 2.3 per cent tin, the ore being prepared in theform of a pulp and fed into the usual flotation machine together withthree pounds of sulfuric acid per ton of dry ore, together with 2.4pounds methyliso-butyl ketone and three pounds of oleic acid per ton ofdry ore. In such case a froth will form which contains a concentratecontaining approximately sixty per cent of tin.

The amount of reagents employed and particularly the amount of activeacid, may be varied to obtain the desired result. Even a separation ofmagnetite from andradite garnet may be made and in this caseapproximately thirty pounds of hydrochloric acid per ton of dry ore wasfound to give the best results when using a moderate amount of frothingand collecting agents.

The process of this invention makes it possible to recover heavy mineraloxide ores by flotation with results comparable to those obtained withsulfide ores which have heretofore been considered to be much moreeasily separated by flotation. This invention depends to an extent uponthe fact that the oxide minerals when in acid pulps exhibit surfacephenomena which distinguish them from'the usual gangue materials andwhichphenomena do not occur in neutral or alkaline solutions, but theinvention is also dependent upon the discovery that an effective frothcan be maintained in spite of the presence of active acid in substantialamounts. The froth which is removed in the process of this invention maybe retreated, if it is desired, to increase the percentage of heavymineral metal oxide in the concentrate, or the tailings may beretreated, if it is desired, to increase the percentage of mineralrecovered.

Herein in the specification and claims the term active acid" is intendedto mean one or more of the group consisting of hydrochloric,hydrofluoric, sulfuric, phosphoric, nitric, acetic, and tartaric acids.The term Water-insoluble liquid ketone as used herein is intended tomean such ketones as are liquid at ordinary temperatures and whichdissolve in water no more than economical operation of the processpermits, in-

cluding those mentioned or referred to above.

The process of this invention has been described in detail above inconnection with specific instances in which it may at times be usefullyemployed. It is not intended, however, that the protection of LettersPatent to be granted hereon be unnecessarily limited thereby, but it isintended that said protection should extend to the full field of theinvention as represented by the scope of the claims appended hereto.

What I claim as my invention is:

1. The process of separating the mineral constituents of an orecontaining a heavy mineral metal oxide which consists in mixing the orein a finely divided state with water so as to form a pulp, agitating thepulp in the presence of an active acid, a water-insoluble liquid ketoneand a saponiflable substance, supplying the pulp with air to produce afroth containing a concentrate, and removing the froth.

2. The process of separating the mineral constituents of an orecontaining heavy mineral metal oxide wh'zh consists in mixing the ore ina finely divided state with water so as to form a pulp, agitating thepulp in the presence of over one pound of active acid per ton of dryore, a water-insoluble liquid lzetone, a saponiflable substance,supplying the pulp with air produce a froth containing a concentrate,and removing the froth.

3. The process of separating the mineral :onstituents of an orecontaining a heavy mineral metal oxide which consists in mix ng the orein a finely divided state with water so as to form a pulp, agitating thepulp in the presence of an active acid, a water-insoluble liquid ketoneand a fatty acid substance, supplying the pulp with air to produce afroth containing a concentrate, and removing the froth. a

4. The process of separating the mineral constituents 01' an orecontaining a heavy mineral metal oxide which consists in mixing the orein a finely divided state with water so as to form a pulp, agitating thepulp in the presence of an active acid, a dipropyl ketone and asaponinable substance, supplying the pulp with air to produce a irdthcontaining a concentrate, and removing the froth.

5. "Elle process of separating cassiterite from cessiterite ore whichconsists in mixing the ore in a flnely divided state with water so as toform a pulp, agitating the pulp in the presence of an active acid,dipropyl ketone and oleic acid, supplying the pulp with air to produce afroth with the cassiterite floating therein, and removing the froth.

6. The process of separating cassiterite from cassiterite ore whichconsists in mixing the ore in a finely divided state with water so as toform a pulp, agitating the pulp in the presence or over one pound ofsulfuric acid per ton of dry ore, dipropyl ketone and oleic acid,supplying the pulp with air to produce a froth with the cassiteritefioatingtherein, and removing the froth.

' JOHN MARK PATEK.

